Distillation of tar



0611.25, 1932. v A H 1,884,220

DISTILLATION OF TAR Filed May 31, 1929 4 Sheets-Sheet l TIwrr 0/7ondomer Jaw/ 7, Chamber INVENTOR ATTORNEYS Oct. 25, 1932. A. H. RADASCHDISTILLATION OF TAR Filed May 31, 1929 4 Sheets-Sheet 2 5cm; (Zamer gINVENTOR I ATTORNEYS Oct.'25, 1932. A. H. RADASCH DISTILLATION OF TARFiled May 51, 1929 4 Sheets-Sheet 3 M14 W BY ATTORN EYS mama a. 25, 1952UNITED STATES PATENT OFFICE AB'IHOR H. RADASCH, OF SOUTH ORANGE, NEWJERSEY, ASSIGNOB IO THE BASKET-l COMPANY, OI! NEW YORK, N. Y ACORPORATION OF NEW JERSEY DISTIIILATION OI TAB Application filed m 81,1929. flerial N0.'88'i,868.

- lation plant. The invention includes both the process and apparatusfor carrying it out. According to the presentjinvention tars ofdifferent composition are; separately recovered from coal distillationgases and se arately distilled to produce oils and pitc es.

The invention is described more particularly as applied to a coke ovenplant.

In the operation of coal distillation plants such as coke oven plants,the production of coke is in man cases the primary operation, while ingas p ants, the production of gas is a primary operation. In both casescoke and gas are produced and tar is recovered as a by-product. The taris recovered by cooling the gases to condense and separate the tartherefrom;

The tarproduced at coal distillation plants is to a large extent used asa fuel, particularly where coke oven plants arelocated adjacent tosteelmills, in which case the tar is extensively employed as a fuel in 0 enhearth and other furnaces. A substantial proportion, however, of the tarrecovered as a byproduct at coke oven and gas lants is shipped to tardistillation plants an there subjected tov distillation for theproduction of distillate oils and pitch residues therefrom.

According to the present invention, the tar is not collected as a totaltar product at the coal distillation plants but the tar is collected inseparate fractions, one of which is a heavy tar and another of which isa light tar or tarry oil and these res ctive heavy and light tars areseparately distilled to pitch and the vapors resulting from the separatedistillations are together cooled to roduce one or more distillatefractions. l itches of the same or different melting points may beprepared from the different tars. The distillation of the separatetarfractions is advantageousl carried out directly at the coaldistillation plant by subjecting the separate tar fractions to directcontact with the hot coal distillation gases,

distilling the tar fractions.

In the ordinary by-product coke oven plant the gases are collected froma number of coke ovens in acollector main and are there cooled byammonia liquor or by ammonia liquor and tar and a considerable part ofthe tar constituents separated from the gases in the form of a heavytar. The gases are then passed thru a cross-over main to condenserswhere they are further cooled and where additional tar is separatedtherefrom usuall in the form of a light tar or tarry oil. The heavy tarseparated in the collector main and the light tar separated in thecondensers are commonly combined and sold or employed as tar. bining theheavy tar and the light tar, I keep these tar fractions separate and Itake advantage of their difierence in character by sub ecting themseparately to distillation thereby efiiciently distillin the tar andrecovering distillate oil an The vapors resulting from the separate distillations may be cooled in the same condensing system to produce a'single oil product or by fractional cooling more than one oil fractionmay be obtained.

The heavy tar separated from the gases in the collector main, which incoke oven operations may amount to or or more of the total tar, isrelatively low in oil content and relatively high in pitch constituents,while the light tar or tarry oil separated in the condensers of aby-product coke oven battery contains a large proportion of oils and arelatively low percentage of pitch contain only a smaller amount ofhigher boil ing constituents, is more readily volatilized from such oilsthan oils of similar boiling range can be volatilized from tarscontaining a larger percentage of higher-boiling oils, as for examplethe tar from the collector main, or the tar formed by blending theinstead of com-' pitch products.

i the pitch produced by present invention in distilling the lighter'stilledvfrom a mixture of this tar fraction of lower boilin range and atar com rising oils of higl er boiling range. T erefore by separate ydistilling the tar fractions, the lighter tars are distilled at a lowertemperature and the maximum amount of tar ma be distilled with any givenquantlty of eat. I

According to this invention the vapors resultin from the separate'di'stillations are coole to ether in a single condensing apparatus anthe distillate oils are obtained as one or more fractions Because of thelower temperature re uired for distillation of the lower boiling oi 5present in the lower bOllIIlg tar fraction, when the fractions areseparately distilled any decomposition of the vapors which would resultfrom heating to higher temperatures is avoided. This results in anincreased oil yield and the production of an oilfree from the resultindecom osition products. The amount an composition of the distillation isaffeoted correspondingly.

According to the usual continuous methods of distilling tar, it isnecessary to maintain the vapors resulting from the distillation at arelatively high tem erature, 1. e., the temperature at which the iherboihng 0113 are distilled from the tar. ccordmg to the action or iihter fractions of tar, the temerature at w iich the gases are maintainedis less than that necessary in those other methods in which a largeramount of heavier tar is blended with the lighter tar. By separatelydistilling the lighter tar and the heavier tar less decomposition of thevapors results since it is not necessaryto maintain all of the vapors atthe higher temperature necessary with such other methods. 7 Al ho theseparate distillations of the heavier and lighter tar fractions may becarried out in various ways accordin to this invention, it isadvantageous to subject the different tar fractions to distillation I)bringing them into intimate contact with hot coal distillation aseswhile these gases are at a sufliciently high temperature to efi'ect thede sired distillation. By bringing the tar fractions into intimatecontact with the hot gases, for example, by repeatedly spraying the tarinto the gases while they are at a high temperature approximating thatat which they come from the ovens or retorts, the gases themselves willbe scrubbed and freed to a greater or less extent from their heavierentrained carbon and itch particles, while the tar frac tions themse veswill be rapidly distilled with melting point, or pitc resultinenrichment of the gases in oil vapors. ere will be obtained a pitchresidue comprising undistilled constituents of the tar and suchadditional pitch constituents as are scrubbed from the gases. Onsubsequently cooling the gases, distillate oils will be obtained whichare low in tar content and which may be substantially free from tarcontaminations, i. e., the oils may be clean oils and directlymerchantable as creosote oils or for other purposes.

The heavier and lighter tars may be distilled to pitches ofapproximately the same es of different melting %oints may be made fromthe different tars. y combining the ases and vapors resulting from theseparate fistillations of the tar fractions and cooling the gases so asto fractionally condense the oils therefrom, I am able to obtaindistillate oil fractions directly from the gases while employing onlyone condensing system. Instead of separately distilling the tarfractions andcomblning the resulting gases and vapors, I may distill thedifferent tar fractions in the same gasesfas, forexample, by firstdistilling a heavier tar fraction in the gases and then cmp'lloying thepartially cooled gases .to disti a tar fraction of lower boiling range.The use of one condensing system obviates the expense of two or morecondensing systems which are necessary when the gases and vapors fromthe sep arate distillations are separately cooled.

The application of the present invention to the usual coal distillationplant does not require any substantial change or modification in theby-product recovery system or in the o eration of such a system so faras the hand ing of the gases is concerned, except for the provision ofseparate collectin means for collecting and keeping separate t 0 heavyand light tar fractions. Separate storage tanks or collect-ing tanks maybe provided for the heavy tar from the collector main and the light tarfrom the condensers and where two or more fractions are obtained in thecondensers, se arate stora e tanks may be provided for t e difierentractions.

Where the ases from the coal distillation plant are emp oyed fordistilling the separate tar fractions, provision must be made for usingthe gases while at a sufiiciently high temerature. It is advantageous tospray the tar mto the gases and to effect such intimate contact betweenthe tar and gases as to scrub and detar the ases simultaneously with thedistillation o the tar. In coke oven plants the gases. leave the cokeoven at a high temperature around (SOD-700 C(or higher. By drawing offthe gases from the ovens directly into a distillation chamber withoutpermitting an considerable cooling of the gases and b bringing the tarinto intimate contact with the gases while they are still at a hi htemperature, the tar can be rapidly dist ed and a pitch residue producedtherefrom at the same time that the gases are themselves scrubbed andfreed more or less completely from suspended pitch particles and reatlyenriched in oil vapors by the disti ation.

' Separate stills are provided for the separate tar fractions and inconnection with these stills a single condensing system is provided forthe distillate oils resulting from the distillations. By regulating therate at which the tar is sprayed into the gases, etc., the heavy tar canbe distilled in gases which are maintained at a higher temperature andthe light tar or tarry oil or the various fractions of 'melting pointpitch is produced it is advantageous to pass the tar and the gases thruthe still in a enerally concurrent direction. If the tar and gases passthru the still in a counter-current direction, the hot fresh gases whichhave a low vapor content come into contact with the nearly completelydistilled pitch and difiiculties may arise from over-distillation of thepitch and the formation of coke as a result of the-action of the freshhot gases on the nearly completely distilled pitch.

. Where, on the other hand, the gases and vapors resulting from thedistillation and also the pitch are withdrawn from the same end of thestill, the nearly completely formed pitch comes into contact with thenearl saturated gases cooled by previous distillation of tar. Thetendency to form coke or carbonaceous deposits is therefore greatlylessened.

" Furthermore, the fresh hot gases come into contact with the fresh tarand the tendency to form coke at this end of the still isalso small.

Where hot coal distillation gases are employed for distilling a totaltar such as that produced by blending the various .tars condensed fromcoke oven gases and where a high melting oint pitch is produced, theitch and enriche gases are advantageous y withdrawn from the same end ofthe still and the nearly completely distilled tar comes in contact withases containing a considerable rcentage 0 higher boiling constituents. Wibn the heat of the gases is efiiciently used, the

gases leaving the still are almost saturated with such higher boilingoils. For this reason it is necessary to carry out the distillation at ahigh temperature in order to distill from the pitch the last traces ofhigher boiling oils the removal of which is necessary to roduce thatparticular pitch. On the other iiand, if instead of distillin the total.tar, various tar fractions are istilled, the gases and percentage of hi'her boiling oils as they eave the still. e distillation of the lasttraces of higher boiling oils, in order to produce a correspondingpitch, takes place at a. lower temperature.

The extent to which the distillation of the respective tars is carriedcan be regulated and controlled dependin upon the character ofdistillate oils desire and the pitch residues to be produced. Where themaximum oil yield is desired, both the heavy and light tars can bedistilled to pitches of high melting point, for example, around 400 F.,or higher. Where pitches. of lower meltin desired, the heavy tar may besu jected to a minimum of distillation to produce such low melting.point pitch. The temperature necessary to distill the lower boiling oilsfrom heavier tar is higher than that required to distill the same oilsfrom a lighter tar but the time during which this heavier tar is heatedto eflect the distillation is short. The time reTlired to distilllighter tars to pitch may be onger than the time required to distillheavier tar, but the temperature necessary is not so great.

Where the tar is to bedistilled in hot coke oven gases, and thetemperature of the gases is uniform, a large quantity of the light tarmay be sprayed into the hot gases in the form of a fine spray, so thatthe temperature of the taneous y to the temperature ran e desired. Thequantit of light tar distille per unit of time, by t is process, will belarge.

Li ht tar may advantageously be distilled to a igh meltlng oint pitch,while heavy tar is bein distille to a lower melting point pitch. Highmelting point pitch may be made from li ht tar. w1th comparative easeand with a re atively high percent recovery of distillate oil. This isdue-to the fact that the oils to be distilled are of relatively lowerboiling range than are those present in the heavier tars. These oilsrecoveredfrom the lighter tars are relatively more valuable commerciallythan are the oils from the heavier tars.

point areases will be reduced almost instan- Therefore the distillationto harder pitches yields valuable oils at high percent and on cooling acomposite oil will be pro duced. The gases may first be employed fordistillin a heavier tar fraction to a relatively high meTting pointpitch, and the resulting gases be then employed for distilling a lightertar or tarry oil to a pitch of lower melting point, although in such acase some destruction of heavy oils in the heavy tars will beexperienced. The vapors from both distillations will be treated in thesame condensing system.

Where the collection of separate pitches is not important, but efiicientdistillation is desired, the lighter tar or tarry oil may be onlypartially distilled in the one still to remove in which heavy tar. issimultaneously distilled is particularly advantageous where a highmelting point pitch is desired. In such a process, the temperature ofthe still employed for distilling the tarry oil need not be high enoughto produce a high melting point pitch therein, but merely high enough todistill oil the lower boiling oils, and such distillation can be carriedon most efliciently therein.

Whether one pitch product is obtained in this manner, or the heavy andlight tars are separately distilled to pitches of the same meltingpoint, or pitches of different melting point, separate distillation ofthe tar fractions is more efiicient than the preparation ofcorresponding pitches by distillation of a total tar comprising theseveral tar fractions. The oil yields are higher and the heatconsumptionis less.

Theinvention will be further described in connection with a by-productcoke oven plant. It will be understood by those skilled in the art thatthe invention is applicable to other types of coke ovens and other coalcarbonizetion plants in which various grades of tar may be fractionallyseparated from the gases as in a gas collector main and a condensingsystem.

In the accompanying drawings,

Fig. 1 is a general plan view of a somewhat conventional charactershowing a byproduct coke oven plant provided with separate collectingand handling equi ment for collecting and keeping separate the eavy andlight tars and for separately subjecting these to distillation andcombining the gases and vapors resulting from the distillation andsimultaneously cooling them in a single condensing system;

Fig. 2 is an elevation of the still shown in Fig. 3 is an end view ofthe still; and

Figs. 4 and 5 show a modified form of apparatus.

Referring to the drawings, 5 indicates a coke oven battery equipped withthe usual uptake pipes 6 and collector main 7 provided with center-box8, from which a cross-over main 9 connects in the usual way withcondensers 10. The goose-necks of the uptake pipes and the collectormain 7 may be sprayed with ammonia liquor, or tar and ammonia liquor,through sprays 11 and 12. The heavy tar and the ammonia liquor, whichdrain from the collector main into the center box 8 are drawn ofi' thrupipe 14 to the decanter 15. Tar and ammonia liquor from the crossovermain may also be drawn off into this same decanter thru pipe 16, or maybe separately collected, or may be collected with the light tar from thecondensers 10. The ammonia liquor and tar will be drawn oif from thedecanter 15 to separate storage tanks 17 and 18.

Light tar or tarry oil and ammonia liquor are drawn off from thecondensers 10 to the decanter 20 from which the ammonia liquor and lighttar are separately collected in the storage tanks 21 and 22. Anexhauster 23 is provided for drawing the gases thru the system. Meansfor recovering ammonia and light oils (not shown) may be provided beyondthe exhauster.

Stills 24 and 25 are provided at the rear of the ovens. Each ofithesestills'is adapted to receive hot gases frbm several of the ovens of thebattery 5. By properly manipulating the valves 26 in the goose-necks ofthe uptake pipes 6, connected with the usual collector main and valves27' and 28 in the goose-necks 27 and the uptakes 28, which connectselected ovens with the stills at the rear of the ovens, the gases fromthose ovens which are connected with both the usual collector main andone of the stills may be directed to either the usual collector main 7or one of the stills 24 and 25. By means of these valves the amount ofhot gases assing thru the stills may be regulated to e eot the desireddistillation.

Each of the stills is provided with agitating means for bringing the tarinto intimate contact with the hot gases. For this purpose a smooth rollor cylinder 29 is shown, dipping to a slight extent into the tar in eachstill. The-gases are sprayed with tar atomized by rapid rotation of thisroll. The degree and intensity of spray can be regulated by regulatingthe extent to which the roll dips into the tar, and the rate at whichthe roll is rotated. The motor 30 is connected with the main as toresult in substantial deterring of the gases. On cooling the resultinggases, clean oils are obtained. Instead of a smooth cylinder, acorrugated or other cylinder, or [m sprays, or other means, may beemployed for bringing the tar into intimate contact with the hot gases.

In operating the apparatus tarry oil or light tar-from the tank 22 ispumped by pump 1Q 31 into the settling chamber 35, the amount beingregulated by the valve 32 and by the pump. The tar is sprayed into thesettlmg chamber thru line 35' and falls upon the baflles 36'. The gas inpassing up thru the 115 bafies preheats and partially distills the tar.

The tar is collected at the bottom of the settling chamber and is run tostill 25 thru line 25". By proper regulation of the valves 27 and 28 inthose uptake pipes connected to the still and the valves 26 in thecorresponding uptake pipes connected with the usual collector main 7,gas from the deslred number of ovens can be passed thru the still. Bycontrolling both the supply of light tar and the supply of hot gases andthe intimacy of contact, the extent to which the distillation is carriedcan be governed. a

Pitch resulting from the distillation is drawn oft" thru a coke trap andleveling arm 33' into the tank 33. A portion of this pitch may hereturned to the still thru the line 34 for retreatment where this isdesirable. The position of the leveling arm 33' determines the level ofthe tar or pitch in the still. A settling chamber 35 which allows liquidparticles entrained in the gases to settle out and to return to thestill is shown but such settling means is not always required but isdesirable if it is desired to have the oils recovered from the gases bycooling, as free as possible of contaminationby tar or tarry matters.

Heavy tar from the receiver 18 is sup plied thru the lines 39 and 35 tothe settling chamber 35. It passes then thru line 24' to still 24 whereit is distilled to produce pitch. The extent to which the distillationis carried may be regulated in the manner described in connection withthe distillation of the light tars, except that when pitches of highmelting point, e. g. 3OO 4OO F. are produced, the pitch isconvenientlyhandled by granulating it in the trough 42' in a stream ofwater. The pitch and water then flow to tank 41 from which the pitch maybe recovered. When soft or medium pitches are made they may be collectedas liquid pitch in tank 41'.

In case hard pitch or pitch of melting point of 300400 F. is made instill 25, a granulatin'g trough similar to 42 and a granulated pitchtank similar to 41 will be required. In many cases the same tank 41 canbe used.

The gases and vapors of oils of lower boiling range from the still 25are combined with 05 the gases and vapors of oils of higher boiling ranfrom the still 24 and together they pass to t e condensers 37 which arehere shown although othercondensing means may be employed. The gasesfrom the still 24 which are the gases carryin heavier vapors resultingfrom the distillation of heavy tar may advantageously pass thru acondenser 38 before being admitted to the condensers 37 in order thathigher boiling constituents may be recovered from these gases beforecombining them with the gases and vapors from the still 24, althoughcondenser 38 need not be employed if the collection of a separate heavyoil fraction from the heavy tar is not desired.

In the arrangement described the heavy tar from the collector main willbe distilled in the still 24 and the light tar from the condensers willbe distilled in the still 25. Pitches which may be of different meltingpoints are produced as residues'of the dis tillations and they areseparately drawn ofiI' into the tanks 33 and 41 or 41'. Due to thedilferent composition of each of the tars distilled, each still isoperated ditferently. The rate at which the tar is fed to each still,the rate at which pitch is withdrawn, etc, are varied to produce thedesired distillation in the still.

Where only one pitch product is desired, and particularly where a highmelting point pitch is desired, the light tar may advantageously besubjected to a partial distillation in the still 25 to remove only theligher oils therefrom. This partly distilled residue is then passed thruthe line 43 to the still 24 and "further distilled thereinsimultaneously with the heavy tar from the collector main. In thismethod of operation, the condenser 38 may advantageously be employed tocondense the higher boiling oils resulting from the distillation of theresidue carried over by the line 43 to the still 24 and the higherboiling oils contained in the heavier tar. The lower boiling oils arecollected in the condensers 37 which are common to both stills.According to this method, the total pitch residue from the distillationof both tars will be produced in the still 24 and will be drawn oil as atotal pitch product into the tank 41 or into tank 41'. Where only a partof the pitch from the still 25 is further distilled in the still 24,dilferent pitch products will be obtained in the tanks 33 and 41 or 41'.

Figs. 4 and 5 show a modified form of apparatus in which the same hotcoal distillation gases are employed for distilling tars of differentboiling range. The hot gases from selected ovens of the coke ovenbattery 50 pass through the uptake pipes 51 into a hot gas header 52 andthence into the still 53. From this still the hot gases pass to thestill 54 and from there to the condensers 55 and 56. An exhauster 57 isshown for drawing the III a] k ammoinsulated as s own at 58 and thestills 53 and 54 may also be insulated to advantage. Each of the stillsis equipped with a spray roll as shown at 59 and 60 driven by a motor inthe manner described in connection with the stills 24 and 25 of thepreceding figures.

The gases from the ovens of the battery not sent thru the hot gas header52 are collected in the collector main 61. They are cooled in theordinary manner as with ammonia liquor supplied from the line 62. Theammonia 1i uor and heavy tar which separate in the odilector main aredrawn off into the decanter 63. The tar is as arately collected in thestorage tank 64. rom the collector main 61 the gases pass to thecondensers 65. Tarr oil and ammonia from the condensers are co lected inthe decanter 66. From this decanter the tarry oil is separatelycollected in the storage tank 67. This tarry oil is lighter than theheavy tar collected in the tank 64 and comprises oils of lower boilingrange than the oils contained in the heavy tar.

The heavy tar from the tank 64 is distilled in the still 53. This tar issupplied thru the line by the pump 71 and sprayed into the tower 72 thruwhich the hot gases and vapors from the still 53 pass on the way to thestill .54. The tar is advantageously collected in the bottom'of thetower and fed thru the line 7 2 to the still 53 at the end at which thehot gases enter from the hot gas header 52. The tar is sprayed up intothe gases by the roll and the gases, are scrubbed and substantiallydetarred and the heavy tar is distilled. The pitch producedis withdrawnthru the adjustable levellin arm 74 and collected in the trough 75. hegases enter the still 53 at a high temperature and the heavy tar may bedistilled to pitch of a high melting point within the still 53.

Where a bi h melting point pitch is produced it may granulated by suddencooling in a stream of water, supplied thru the pipe 75'. The granulatedpitch and water are drawn ofi thru the trough into suitable means forthe separation of the pitch and the water.

The gases leavin the still 53 and the tower 72 are only artial y cooledand only partiall saturate with oil vapors. They ass to the still 54where they are employed or distilling oils of lower oiling range fromthe tarry oil. The tarry oil is supplied from the storage tank 67 to thestill 54 thru the line 76 by means of the pump 77. The tarry oil ispreferably sprayed into the gases in the tower 73 thru which the gasesand vapors pass as they leave the still 54. The tar is partiallydistilled in the tower and the residue may be drained directly into thestill or it may be drawn off from the bottom of the tower by meanssimilar to those shown in tower 72 and admitted to the still at the endat which the gases and vapors from the tower 72 enter the still. Thegases and vapors enter the still 54 thru the main 78.

According to the arrangement shown in the drawings, the tarry oil issprayed into the gases and va rs in the tower, and drains into the stillt ru the main 7 9 connecting the tower with the still 54. Within thestill the tarry oil is brought into intimate contact with the hot gasesand vapors by means of the rapidlyrotatingk roll 60. The gases andvapors entering t 0 still 54 thru the main 78 ave been somewhat cooled.They are only partially saturated with oils as a result of thedistillation in the still 53 and are employed for distillation of thetarry oil in the still 54. The extent to which the tarry oil can bedistilled depends upon the extent to which the.

at which the tarry oil is supplied to the still 54, its tern erature,etc. The pitch produced in the still 54 ma be a low meltingipoint pitchor a pitch 0 higher melting point. It is withdrawn from the still thruthe leveling arm 80. Where a pitch of low meltin point is produced, itmay advantageously e collected in a cup such as the cup 81 and drainedinto the tank 82.

v The hot distillation gases are first employed for distilling tar fromthe collector main. They are then brou. ht into intimate contact withthe tarry oil an the tarry oil'is distilled. The sea carrying vaporsresulting from the disti ation of the heavy tar and tarry oil pass thruthe tower 73 thru the main 83 into suitable condensers. Indirectcondensers 55 and 56 are here shown for fractional cooling of the gasesand vapors and the recovery of se arate clean oil fractions. The coolingmay so regulated that creosote oil is condensed in the condenser 55 andcollected in the storage tank 84 and an oil boilingin the range ofcarbolic oils separates in t e condenser 56 and is collected in thestorage tank 85. Means for the recovery of ammonia, etc. may be locatedbe end the exhauster 57.

Where further istillation of the pitch resultin from the distillation ofthe tarry oil is desired, this pitch may be further distilled in thestill 53. For this purpose the line 86 and um 87 are shown connectingthe tank 82 with t e line 7 2 which conveys the undistilled. residue ofthe heavy tar from the tower 72 to the still 53. With such equipmentheavy tar from the storage tank 64 may be reheated and partiallydistilled in the tower 2 and then brought into the still 53 thru thepipe 7 2'. This heavy tar which has been partially distilled andpreheated is mixed with the pitch from the still 54 su plied thru theline 86 from the tank 82. Thls pitch is advantageously pumped to thestill 53 while it isstill hot. The gases and vaporsresulting aaaaeaefrom this distillation pass thru the tower 7 2 to the still 54 wherethey are employed for distillation of tarry oil from the tank 67.

' It will thus be seen that the present inven- 5 tion takes advantage ofthe fractional separation of tar in the by-product recovery system of acoal distillation plant to produce two or more separate fractions,keeping these frac tions separate and subjectingthem separately todistillation for the production of distillate oils and one or morepitches, and cooling the vapors from the separate distillations in asinglecondensing system to produce one or more distillate oils. 7

While I have described the invention more particularly in connectionwith a coke-oven plant, it will be understood that it is applicable toother coal distillation plants, as gas retort plants, etc.

I claim:

1. The improved method of producing distillate oils and pitches fromcoal tar which comprises 'fractionally condensing the tar from hot coaldistillation gases and thereby producing a plurality of tarfractions,including a heavy tar and a light tar fraction, subjecting thelight tar to distillation to separate lower boiling constituentstherefrom and to produce a heavy tar or itch, combining such 80 heavytar or pitch with the heavy tar fraction and distillating the mixture,and vcornbining the gases and the vapors resulting from thedistillations and cooling them to separate distillate oils therefrom.

2. The improved method of producing distillate oils and pitch from coaltar which comprises fractionally condensing tar from hot coaldistillation gases and thereby producing a plurality of tar fractionsincluding a heavy 4 tar and a light tar fraction, separately distillingthe heavy tar and light tar fractions,

partially cooling the vapors resulting fromthe distillation of the heavytar fraction to separate a heavy oil, combining the resulting vaporswith the vapors from the distillation of the light tar fraction andcooling thecom bined vapors to produce distillate oils.

3. The improved method of producing dis tillate oils and pitch at a cokeoven plant which comprises fractionally recovering tar tar, subsequentlyfurther coeling the gases to separate a li ht tar or tarry oil, keep ngthe heavy tar and tarry oil separate, bringing the heavy tar into directand intimate contact with hotcoal distillation gases whereby the tar isdistilled and a pitch is produced, bringing the gases and vaporsresulting from this tar fractions into direct and intimate contact,

in series, with the same hot coal distillation gases, uniting the pitchproduced by distillation 'of one of the tar fractions with the other tarfraction and distilling it therewith to produce a pitch product, andcooling the gases and vaporsresulting from the distillationsin acondensing system to separate distillate oils.

In testimony whereof I afiix my signature.

ARTHUR H. RADASCH.

from hot coal distillation gases and thereby producing a plurality oftar fractions including a heavy tar and a light tar fraction, separatelybringing the heavy tar and the light tar fractions into direct andintimate contact, in series, with the same hot coal distillation gases,whereby separate pitch products are produced, and cooling the resultinggases and vapors in a condensing system to separate distillate ,oilsfrom the gases.

4. The improved method of producing distillate oils and pitches at cokeoven plants, which comprises collecting the gases from a plurality ocoke ovens in a gas collector main,

' cooling the gases therein to separate a heavy i

